System and method for operating a diesel engine

Abstract

A power generating set includes an engine operable in response to a flow of fuel to produce a flow of exhaust gas. A generator is coupled to the engine and is operable in response to operation of the engine to produce a total electrical power, a primary load is electrically connected to the generator to receive a portion of the total electrical power, and a secondary load is selectively connected to the generator to receive a portion of the total electrical power. An insulated-gate bipolar transistor (IGBT) is positioned to selectively transition between a connected state and a disconnected state. The secondary load is connected to the generator when the IGBT is in the connected state and is disconnected from the generator when the IGBT is in the disconnected state.

We claim: 
     
       1. A power generating set comprising:
 an engine operable in response to a flow of fuel to produce a flow of exhaust gas; 
 a generator coupled to the engine and operable in response to operation of the engine to produce a total electrical power; 
 a primary load electrically connected to the generator to receive a portion of the total electrical power; 
 a secondary load selectively connected to the generator to receive a portion of the total electrical power; 
 an insulated-gate bipolar transistor (IGBT) positioned to selectively transition between a connected state and a disconnected state, wherein the secondary load is connected to the generator when the IGBT is in the connected state and is disconnected from the generator when the IGBT is in the disconnected state; and 
 a particulate filter positioned to receive the flow of exhaust gas from the engine and to filter particulate matter from the exhaust gas, 
 wherein the primary load follows a cyclical pattern, and wherein the IGBT switches between states to selectively connect and disconnect the entire secondary load to maintain an engine parameter above a predetermined value for a predetermined portion of each cycle of the primary load, and 
 wherein the secondary load is positioned within the flow of exhaust gas to heat the flow of exhaust gas before the exhaust gas enters the particulate filter. 
 
     
     
       2. The power generating set of  claim 1 , wherein the engine is a diesel engine and the total electrical power includes a three phase alternating current. 
     
     
       3. The power generating set of  claim 1 , wherein the engine parameter is an exhaust gas temperature, the predetermined value is a temperature threshold suitable for passive filter regeneration, and the predetermined portion of each cycle is between 10 percent and 30 percent. 
     
     
       4. The power generating set of  claim 1 , wherein the engine parameter is an exhaust gas temperature, the predetermined value is a temperature level suitable for active filter regeneration, and the predetermined portion of each cycle is at least 90 percent. 
     
     
       5. The power generating set of  claim 4 , further comprising a controller operable to vary operation of the engine to allow a portion of the flow of fuel to pass to the particulate filter for active filter regeneration and to control the state of the IGBT. 
     
     
       6. The power generating set of  claim 1 , further comprising a controller operable to apply a pulse width modulation signal to the IGBT to control the state of the IGBT. 
     
     
       7. The power generating set of  claim 1 , wherein the predetermined portion is a high-load portion, wherein the cyclical pattern further has a low-load portion, wherein the heat from the flow of exhaust is sufficient for passive filter regeneration during the high-load portion, and wherein the heat from the flow of exhaust is sufficient for active filter regeneration during the low-load portion. 
     
     
       8. A power generating set comprising:
 a generator operable to produce a total electrical power; 
 a diesel engine operable in response to a flow of fuel to drive the generator and to produce a flow of exhaust gas having an exhaust gas temperature; 
 a particulate filter positioned to receive the flow of exhaust gas from the diesel engine and to filter particulate matter from the exhaust gas; 
 a primary load electrically connected to the generator to receive a portion of the total electrical power, the primary load having a cyclical pattern; 
 a secondary load selectively connected to the generator to selectively receive a portion of the total electrical power; 
 a switching element operable to selectively transition between a connected state and a disconnected state, wherein the secondary load is connected to the generator when the switching element is in the connected state and is disconnected from the generator when the switching element is in the disconnected state; and 
 a controller operable to vary the state of the switching element to maintain an engine at a total load above a predetermined value for a predetermined portion of each cycle of the primary load such that the heat from the flow of exhaust is sufficient to one of passively regenerate or actively regenerate the particulate filter. 
 
     
     
       9. The power generating set of  claim 8 , wherein the switching element includes an insulated-gate bipolar transistor (IGBT). 
     
     
       10. The power generating set of  claim 9 , wherein the controller is operable to apply a pulse width modulation signal to the IGBT to control the state of the IGBT. 
     
     
       11. The power generating set of  claim 8 , wherein the engine parameter is an exhaust gas temperature, the predetermined value is a temperature threshold suitable for passive filter regeneration, and the predetermined portion of each cycle is between 10 percent and 30 percent. 
     
     
       12. The power generating set of  claim 8 , wherein the engine parameter is an exhaust gas temperature, the predetermined value is a temperature level suitable for active filter regeneration, and the predetermined portion of each cycle is at least 90 percent. 
     
     
       13. The power generating set of  claim 12 , wherein the controller is operable to vary operation of the diesel engine to allow a portion of the flow of fuel to pass to the particulate filter for active filter regeneration. 
     
     
       14. The power generating set of  claim 8 , wherein the secondary load is positioned within the flow of exhaust gas to heat the flow of exhaust gas before the exhaust gas enters the particulate filter. 
     
     
       15. The power generating set of  claim 8 , wherein the predetermined portion is a high-load portion, wherein the cyclical pattern further has a low-load portion, wherein the heat from the flow of exhaust is sufficient for passive filter regeneration during the high-load portion, and wherein the heat from the flow of exhaust is sufficient for active filter regeneration during the low-load portion. 
     
     
       16. A method of operating a power generating set, the method comprising:
 operating a diesel engine to drive a generator; 
 generating a total electrical power during generator operation; 
 switching a switching element between a connected state and a disconnected state to selectively direct a portion of the total electrical power to a secondary load when the switching element is in the connected state; 
 directing the remaining total electrical power to a primary load, the primary load having a cyclical pattern; and 
 regenerating a particulate filter by moving the switching element between the connected state and the disconnected state to maintain an engine at a total load above a predetermined value for a predetermined portion of each cycle of the primary load such that the heat from a flow of exhaust from the diesel engine is sufficient to one of passively regenerate or actively regenerate the particulate filter. 
 
     
     
       17. The method of  claim 16 , wherein the switching step includes applying a pulse width modulation signal to an insulated-gate bipolar transistor (IGBT) to control the state of the switching element. 
     
     
       18. The method of  claim 16 , wherein the engine parameter is an exhaust gas temperature, the predetermined value is a temperature threshold suitable for passive filter regeneration, and the predetermined portion of each cycle is between 10 percent and 30 percent. 
     
     
       19. The method of  claim 16 , wherein the engine parameter is an exhaust gas temperature, the predetermined value is a temperature level suitable for active filter regeneration, and the predetermined portion of each cycle is at least 90 percent. 
     
     
       20. The method of  claim 16 , wherein the predetermined portion is a high-load portion, wherein the cyclical pattern further has a low-load portion, wherein the heat from the flow of exhaust is sufficient for passive filter regeneration during the high-load portion, and wherein the heat from the flow of exhaust is sufficient for active filter regeneration during the low-load portion.